Background

Although much is known, there are still many unanswered questions, particularly concerning the basic physical processes that determine the dynamics of the radiation belts. For example, two physical processes which have received a lot of attention are:

  1. cyclotron resonance wave-particle interactions with VLF waves, which lead primarily to energy and pitch-angle transport
  2. drift-resonance wave-particle interactions with ULF perturbations, which lead to radial diffusion

It is generally accepted that both of these processes play important roles in radiation belt dynamics, however their relative contributions are not well understood quantitatively. Recent work has shown that even when VLF local electron energization process are ignored, the transport of relativistic electrons from L=7 into the radiation belt region can be simulated by solving the radial diffusion equation with a relatively simple Kp-dependent electron loss term.